What size is 16:9 in pixels? Common 16:9 and 9:16 sizes

16:9 is a shape, not one size: any frame whose width is 16/9 of its height is 16:9. The common 16:9 sizes are 1280 × 720 (720p), 1920 × 1080 (1080p), 2560 × 1440 (1440p) and 3840 × 2160 (4K), and 9:16 is the same sizes turned upright, such as 1080 × 1920. To generate an image at an exact 16:9 size with Sume, ChatGPT Image 2.5 takes 1280 × 720, 2560 × 1440 or 3840 × 2160 as a custom size, but not 1920 × 1080: ask for 1920 × 1088 and crop 8 pixels.

The named resolutions come from YouTube's help page on video resolution and aspect ratios, and the Sume sizes from the Image API docs, both read on 2026-09-28.

How do I work out a 16:9 size in pixels?

Multiply the height by 16 and divide by 9 to get the width, or multiply the width by 9 and divide by 16 to get the height: 1080 × 16 ÷ 9 = 1920. Sizes where that division isn't whole are only close to 16:9. YouTube lists 480p as 854 × 480, while an exact 16:9 frame 480 pixels high would be 853.33 pixels wide.

What size is 9:16 in pixels?

The same numbers, swapped: 720 × 1280, 1080 × 1920, 1440 × 2560 and 2160 × 3840. 9:16 is a vertical frame, the shape of a phone held upright, so the width is the smaller number. For vertical video sizes and platform specs, see vertical video resolution.

Is 1080p the same as 16:9?

No. 1080p names a height of 1080 pixel rows; 16:9 names a shape. The frame is both only at 1920 × 1080, which is how YouTube lists 1080p. A 1080 × 1350 image is 1080 pixels wide but 4:5, the Instagram portrait shape; AI image aspect ratios covers that one.

How do I make a 16:9 image with AI?

Every image model on Sume lists 16:9 and 9:16 in its aspect_ratio values, so aspect_ratio: "16:9" on POST /v1/images gets the shape. The pixel count then depends on the model and its resolution tier, and the docs do not list 16:9 pixel sizes per tier, or for named presets such as landscape_16_9.

For an exact size, send custom pixels in image_size to ChatGPT Image 2.5 (openai/gpt-image-2.5). Both edges must be multiples of 16, the longest edge at most 3,840, the shape no wider than 3:1, and the total 655,360 to 8,294,400 pixels. That leaves 11 exact 16:9 sizes, each a whole multiple of 256 × 144: 1280 × 720, 1536 × 864, 1792 × 1008, 2048 × 1152, 2304 × 1296, 2560 × 1440, 2816 × 1584, 3072 × 1728, 3328 × 1872, 3584 × 2016 and 3840 × 2160. Swap width and height for 9:16.

curl -X POST "https://api.sume.com/v1/images" \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-image-2.5",
    "prompt": "a wide mountain lake at sunrise, soft mist, no text",
    "image_size": { "width": 2560, "height": 1440 }
  }'

How do I get exactly 1920 × 1080?

1080 is not a multiple of 16, so ChatGPT Image 2.5 won't take 1920 × 1080 as a custom size. Two routes get you there:

• Ask for 1920 × 1088 and crop 8 pixels of height in any image editor, 4 from the top and 4 from the bottom. The AI wallpaper generator post uses the same trick for 1080p screens.
• Or generate 1280 × 720 and enlarge it with Image Upscale 1.0 at upscale_factor: 1.5. Its API reference allows any factor from 1 to 4 but doesn't say how a decimal factor rounds, so check the size you get back. How to upscale an image to an exact size shows the call.
• Either way, /v1/images result URLs are signed, so download the file you keep.